This grant is an application for support of our clinical and laboratory investigative activities in the Southwest Oncology Study Group. Specifically these funds are necessary for our participation in cooperative cancer therapy trials which utilize a combination of surgery, and/or radiation therapy, and/or chemotherapy for the investigative clinical trials of leukemias, lymphomas, and a variety of childhood solid tumors. Emphasis is placed on integrated multi-modality treatment programs in Phase III randomized prospective studies. We are also participating in several pilot studies of new drug treatment programs, in Phase II trials, and non-randomized studies. The clinical response will be related to drug levels determined by mass spectrophotometry in collaboration with the division of Pediatric Pharmacology. In addition to group studies as described above, we are (within this institution) actively involved in the immunological characterization of subtypes of childhood acute lymphocytic leukemia and have already published innovative material in this area. Extensions of our preliminary observations are being extended to a group-wide study. Funding in the area of pediatric immunology is necessary for continued investigation of these leukemia subtypes.